Karimenu II Dam



Crest Length (m)


Reservoir Volume(m3)


Population to Serve


In the Feasibility Study and Master Plan for Developing New Water Sources for Nairobi and Satellite Towns study carried out in 2012, Karimenu II Dam was recommended for development as one of the sources to supply water to Ruiru-Juja towns and the adjoining areas. The Karimenu II Dam Water Supply Project is located in Kiambu County, Central Province of Kenya, 75Km North of Nairobi. The proposed Karimenu II Dam will be constructed across Karimenu River.

Karimenu II Dam is being implemented under the EPC-F framework by Joint Venture between M/s AVIC International Holding Corporation (AVIC) and M/s Shanghai Municipal Engineering Design Institute (SMEDI) with financing from China Exim Bank and the Government of Kenya.

The contract was signed on 9th May 2014 with a construction period of 36 months and 12 month Defects Notification Period. The construction works commenced in May, 2019 and are scheduled to be completed by May, 2022.

Current Status:

Overall progress of works: 96%

Dam works: 100%

Water treatment works: 96%

Pipeline: 77%

Ruiru Reservoir: 100%

Juja Reservoir: 60%

The project executing agency is the Athi Water Works Development Agency (AWWDA).

Supply area: this will cover Kiambu County and Nairobi County. The treated water will be supplied as follows:

  • Ruiru: 35,250m 3 /d
  • Juja: 11,750m 3 /d
  • Nairobi: 23,000m 3 /d

Project Impact: The project will serve an additional 850,000 people in Ruiru, Juja and Parts of Nairobi.


The School has been constructed by AWWDA as the project’s CSR to the host community. The overall progress is at 100% complete with construction of the following facilities complete:
22No. Classrooms
Administration Block
Multipurpose Hall
A fully fledged Pre-School Unit with a secluded playfield
A Library Room
A Computer Laboratory Room
A Science Laboratory Room
Modern Sanitation Facilities
Provision for Playfields: football, Netball & Volleyball pitch

The School sits on approx. 2.7Ha and will host a population of approximately 1000 pupils. All the facilities will be furnished.

Scope of Works


The project has the following main components:

  • Dam to create a water reservoir with storage of 26.5Mm3.
  • Water treatment plant of capacity 70,000m3/day.
  • Approximately 70.2km DN 1000/500mm of raw and treated water transmission pipelines.
  • Two terminal tanks of capacities 23,500m3 and 3,000m3 in Ruiru and Juja respectively.

Detailed Scope of Works - Dam

The Dam consists of the following components:

  • Water supply tunnel about 408m long, water intake tower and trestle bridge on piers;
  • 54m high, clay core rockfill Dam;
  • Spillway;
  • Miscellaneous works i.e. Administration building, roads, electromechanical equipment,

Water Treatment Plant

The Water Treatment Plant consists of the following components:

  • The inlet structures; Sedimentation tank and V-type filtering tank and backwash pump house;
  • Clean water tank, Chemical dosing and storage building; Waste water lagoon; Sludge drying bed;
  • Auxiliary buildings.


The approximately 70.2 km pipeline consists of the following components:

  • DN1000mm raw water pipeline 490m long;
  • DN800mm treated water pipeline 41.9km long;
  • DN700mm treated water pipeline 7.6km long;
  • DN600mm treated water pipeline 6.4km long;
  • DN500mm treated water pipeline 14.3km long;
  • Water tank located at Bennett’s ridge with a volume of 23,500m3.

Environmental Aspects

A robust team from the Client, Contractor and Consultant had been formulated to ensure that’s the project is implemented in line with existing Laws and regulations on matters environment, health and safety.

AWWDA has identified potential sources of pollution in the dam catchment area and will liaise with the relevant authorities to formulate a multi stakeholder conservation strategy.

Baseline surveys have also been conducted and management plans formulated and Contractor’s compliance is monitored on a continuous basis.

Benefits to Host Communities

In addition to supplying 70,000m3/day of water to Ruiru, Juja and Nairobi, other host communities are benefiting through augmentation of various water supply systems, these include but are not limited to:

  • Construction of approximately 280Km of water transmission and distribution pipelines in Gatundu Area
  • Drilling and equipping of 6No boreholes in Gatundu
  • Construction of Wangui – Gichogocho Community Water Project: entailing Intake, 
  • Rehabilitation of raw water main under the Ruobora water supply system to restore the supply of 1200M3/d;
  • Administration office and accommodation for Critical infrastructure police unit.